Detergent bars or cakes



Patented Sept. 25, 1945 DETERGENT BARS R CAKES Emil Edward Dreger, Summit, N. .I., and Adam .Carr Bell, Jackson Heights, N. Y., assignors to Colgate-Palmolive-Peet Company, Jersey City, N. J., a corporation of Delaware No Drawing. Application May 3, 1941, Serial No. 391,704

7 Claims.

This invention relates to novel bars and cakes of synthetic detergents, and more particularly to bars and cakes containing the solid salts of sulphated diglycerides.

Within the last few years a large number of synthetic detergents have been developed and are now commercially available. These synthetic detergents, generally termed sulphonates whether or not they are true sulphonates or sulphates, or mixtures, possess advantages under certain circumstances over soap, especially when used in hard water, since their calcium and magnesium salts are generally water-soluble. In a great many I instances they have been found to be more desirable than soap. In all of those uses, however, where they have in part or completely supplanted soap, the specific form of the compound or composition has been relatively, if not completely, immaterial.

Generally, these new synthetic detergents are sold in a finely divided form such as powder, beads or flakes. There is one use in which these detergents have not as yet approached the desirability of soap, and that is for toilet purposes such as are now served by toilet soap in the form of cakes and bars.

The desirability of soap in the form of cakes and bars depends primarily upon that characteristic of soap which permits reuse. When the soap is used, the surface thereof is wetted to dissolve or soften a comparatively small quantity, which is transferred to the person of the user or to the fabric or other article being cleaned. Thereafter, when the soap is not in use, it will dry out sufliciently to permit subsequent handling without a further deposit of the soap until it is again wetted with water.

Commercially available synthetic detergents are not suited to the production of bars and cakes without the addition of foreign matter inquantitles sufficient to overcome the deficiencies of the synthetic detergents themselve for this purpose. The most important of these deficiencies are: (l) the synthetic detergents are so soluble in water that they dissolve too rapidly, thus wasting the bar and resulting an uneconomical bar or cake; (2) their physical properties do not permit their treatment in apparatus and processes used in soap making, such as milling operations, plodding, etc.; and (3) even after they are formed into bars and cakes a sticky characteristic renders them undesirable for use.

Applicants have discovered that the salts of the sulphuric acid esters of glycerol which has been esteriiied by two fatty acid molecules, when the fatty acids are properly chosen, can be formed into a commercially desirable bar or cake. Such a bar or cake possesses all the desirable properties of a bar or cake of soap and retains all those properties of the compound which make synthetic detergents more desirable in certain uses than soap. Moreover, the solid salts of these compounds can be satisfactorily treated by the usual soap making operations, such as milling and plodding, which are necessary or advantageous in making desirable bars and cakes. Also, they are not sticky when formed into bars or cakes.

According to the preferred process of this invention, the salt or salts of the sulphuric acid esters of dlglycerides are prepared by reacting glycerine, fatty acids, and sulphuric acid, in the proper proportions; or by reacting glycerine, a fatty oil such as coconut oil, and sulphuric acid, in the proper proportionsj or by reacting glycerine and fatty acids or fatty oil, an thereafter sulphating the diglyceride. The proportions chosen, as will be illustrated hereinafter in the examples, are those which produce diglycerides of fatty acids and the mono-sulphate thereof.

In the production of these compounds, certain advantages may be realized by a selection of the fatty acids to be esterifled with the glycerol. For example, the salts of the sulphuric acid esters of a diglyceride containing two caproic acid radicals form bars and cakes which are not nearly so desirable as those containing longer-chain fatty acid radicals, because of lack of desirable foaming and washing or cleansing qualities. Apparently the water-solubility of these compounds decreases with increase in the length of the fatty acid chains, Or as the sum of the carbon atoms in the fatty acid radicals increases; consequently, the firmness or hardness of the bar made therefrom increases in the same way. However, a certain water-solubility must be maintained in order to obtain the best lathering and cleansing properties.

For instance, the salts of the sulphuric acid ester of dilaurin (dilauric acid ester of glycerine) may be formed into an especially desirable bar or cake. This compound possesses suflicient water-solubility to function as an excellent detergent. On the other hand, when formed into a bar or cake by extrusion or by pressing, it will dry out after use and retain no stickiness or other undesirable characteristics heretofore encountered in attempts to make synthetic detergents into bars or cakes.

It is unnecessary to have two fatty acid radicals of the same number of carbon atoms in the compound. In preparing bars or cakes from diglyceride sulphates containing different fatty acid radicals, it is especially desirable to regulate the product so that the two fatty acid radicals will contain a total of about 18 to about 28 carbon atoms, and one of these fatty acid radicals should contain at least about 12 carbon atoms. Thus, the compound may contain one myristic acid radical and one caproic acid radical, making a total of 20 carbon atoms in the two acid radicals. If stearic acid is employed in making these compounds, it should be used with caproic or caprylic acid so as to form a compound containing one stearic acid radical and one caproic or caprylic acid radical, or a mixture of compounds containing those acids in the ratio of one to one. Even within the approximate range of 18 to 28 (total) carbon atoms in the two radicals, which applicant has found to be especially desirable, optimum results are obtained by producing a compound having about the sum of 24 carbon atoms in the two acid radicals.

The following formula depicts the structure of the solid organic sulphate compounds employed in the present invention for preparing detergent bars and cakes:

wherein R and R are long-chain fatty acid radicals and X is the cation of an alkaline substance.

Bars or cakes produced according to this invention retain the advantages found in most synthetic detergents, i. e. good solubility and utility in hard water. They can be made with a much smaller water content than is common in toilet soap bars, and they last longer than soap bars or cakes of the same size. Furthermore, this invention permits the use of short-chain fatty acids such as caproic, caprylic and capric, or even butyric, which are of little or no use in the production of soap. Although these compounds in bar or cake form may be produced in substantially anhydrous condition or with a water content of several per cent, it is desirable and advantageous to limit the water content to a few per cent, such as about one and one-half per cent. This increases the tendency of the bar to dry out after use, simpliflies its preparation, and enhances its value to the consumer over bars with a greater water content.

Inasmuch as the sulphates of diglycerides are substantially neutral or slightly acidic in character, the bars and cakes prepared according to this invention are particularly suitable for toilet use because of their reduced tendency to change the normal pH of the skin, as compared with that of more alkaline cleansing agents. Substances which modify the efl'ect of these synthetic detergents may be added thereto during the manufacture of bars or cakes therefrom. For example, superfatting agents, including lecithin, lanolin, olive oil, cocoa butter, Vaseline, mineral oil and stearic acid, sulphonated castor oil, and the like, may be incorporated in these bars and cakes to prepare them for particular purposes.

Coloring matter, inorganic and/or organic, may be utilized to give to the finished bars and cakes pleasing colors or tints. Some coloring material such as titanium dioxide gives additional hardness to bars and cakes formed from certain compounds within the sphere of this invention. Tin salts, including the chlorides, sulphates, etc., and

other tin compounds, including tin stearates, palmitates, etc., may be added.

Glycerine may be added to impart emollient characteristics to the bars or cakes and to give them added gloss. Germicides which are stable under neutral or acid conditions may be included.

It should not be understood that these novel bars and cakes must be in the slightly acid, neutral or substantially neutral state, for they may, by the addition of suitable alkaline agents, be prepared in any desirable alkaline pH. Likewise, the pH of these bars and cakes may be further adjusted to the acid side.

Monoand/or diglycerides of long-chain fatty acids, such as those fatty acids found in coconut oil, olive oil, palm oil, cottonseed oil, soya bean oil, processed fish oils (such as hydrogenated fish oils) tallow, etc., may be added to the particular compounds herein described before making them into bars and cakes. Soaps of these acids, other synthetic detergents, including the solid salts of sulphated long-chain fatty alcohols (Gardinols) of sulphonated and sulphated mineral oils, of sulphonated and sulphated alkylated aromatic compounds, of sulphonated oleflnes, of sulphonated and sulphated monoglycerides, and the like, may also be included in these novel bars and cakes.

When ingredients are included which tend to soften these bars and cakes, the sulphated diglycerides may be designed to overcome this effect. This can be done by including in the compound a greater proportion of longer-chain fatty acids.

Although the sodium salts of these diglyceridesulphuric acid esters are for many purposes preferred, other salts may be employed, and may be advantageous in specific uses; 1. e., calcium, magnesium, ammonium, ethanolamine, amine, and others, or mixtures thereof, may be used.

The following examples illustrate the produc tion of the compounds which are utilizedin this invention and in no case are intended to be limiting thereon.

Example I 37.8 gms. of 98% glycerine were added to 434.8 gins, of 20% oleum with cooling. 162.8 gms. of melted lauric acid were added at such a rate that the temperature did not exceed 50 C. The mixture was stirred at about this temperature for an hour and then neutralized to a pH of 6 to 6.3 with a 20% solution of sodium hydroxide. Substantially all of the sodium sulphate formed in the neutralization step was removed by extracting the active ingredient with isopropyl alcohol. (The final product or bar contained about 10% anhydrous sodium sulphate by weight.) Thereafter the water and isopropyl alcohol were removed by drying.

Bars and cakes made from this dilaurin sulphate (sodium salt) by pressing were firm and dried satisfactorily after use.

Example II 3 parts by weight of glycerine were added to parts by weight of 8% oleum, the mixture being chilled while the glycerine was added. 43.2 parts by weight of coconut oil were run into the oleum glycerine mixture which was then warmed to about 50 C. and maintained at that temperature while the mass was stirred for about one hour. This reaction mixture was then neutralized with a 25% solution of sodium hydroxide and the active ingredients (the diglyceride sulphates) were extracted with isopropanol.

After the isopropanol and water were removed, the dried product was formed into cakes. These cakes were hard, lathered freely, ave clear solutions in hard water. and dried satisfactorily after use.

Erample III I 4.9 parts by weight of glycerine (98%) were added to 111 parts by weight of chilled oleum and thereafter the melted mixture of 21.6 parts by weight of coconut oil and 20.4 parts by weight of triple-pressed stearic acid was added to the oleum glycerol mixture over a period of about thirty minutes. This mixture was neutralized with a 25% sodium hydroxide solution.

After separation of the active ingredients by extraction with isopropanol, and drying, the product was made into bars.

Processes and apparatus commonly employed in the soap industry for making milled toilet soap may be utilized in forming these diglyceride sulphates into bars and cakes, as is shown by the following example, which is illustrative only:

A composition containing the following -ingredients:

- Per cent Dilaurin sulphate (sodium salt) 94.50 Titanium dioxide (containing a small quantity of Ultramarine Blue) 0.25

Italian ta 2.00 Water 1.00 Perfume I 1.00 Coloring materials 1.25

was prepared by mixing the dllaurin sulphate, titanium dioxide and water first in a soap amalgamator, and then adding the other ingredients thereto, with mixing. This mixture was milled in the same manner as toilet soap, plodded, ex-

,truded in bar form and die pressed. These bars were firm, non-sticky, lathered freely in hard water and dried to satisfactory condition after A similar procedure was followed in forming sessed all the properties of the dilaurln sulphate as to latherlng, cleansing ability, etc.

A mixture consisting-of the following ingredlents:

' I Per cent Dilaurin sulphate (sodium salt) 86.50

00101111 materials.....

was prepared, milled, plodded and formed into bars and cakes, as in the above described procedure. These bars or cakes were firm, exhibited good foaming and washing characteristics, and dried satisfactorily after use. The emollient infiuence of the olive oil was evident.

While a small quantity .of water is very desirable in producing a suitable consistency in the mixture for milling, plodding and pressing, the water content should not be so great that the resulting mixture is too liquid or the bars unsatisfactorily soft. The final bars or cakes preferably contain only a fraction of one per cent to three or four per cent water.

For the purpose of this application, long-chain fatty acids include those containing at least four carbon atoms. The maximum number of carbon atoms which may be present in one of the fatty acid radicals has not been definitely established, but it is believed that the efllciency of the detergent in the bar decreases as the number of carbon atoms is increased Over about twenty-two.

We claim:

1. Detergent bars or cakes containing as a major ingredient solid salts of the sulphuric acid ester of diglycerides of long-chain fatty acids.

2. Detergent bars or cakes containing as major ingredients solid compounds having the formula:

wherein R and R are long-chain fatty acid radicals and X is the cation of an alkaline substance.

3. Detergent bars or cakes as defined in claim 2 in which the sum of the carbon atoms in R and R is from sixteen to twenty-six, one of which contains at least twelve carbon atoms.

4. Detergent bars or cakes as defined in claim 2 in which the sum of the carbon atoms in R and R is twenty-two.

5. Detergent bars or cakes containing as a major ingredient the solid salts of the sulphuric acid esters of diglycerides, radical contains at least four carbon atoms, and the other fatty acid radical contains at least twelve carbon atoms.

'6. Detergent bars or cakes containing as a major ingredient the solid salts of the sulphuric acid esters of dila 7. A detergent bar of approximately the followingcomposition:

Per cent Sodium salt of dilaurin sulphate 88.50 Olive oil 10.00 itanium dioxide -1 0.25 Water 1.00 Perfume Coloring material 1.25

EMIL EDWARD DREGER.

ADAM CARR BELL.

wherein one fatty acid 

